Indoor Air Quality and Volatile Organic Compounds

Experts in Environmental Sensing Summary

People spend 90% of their time indoors where concentrations of gaseous pollutants are significantly higher than outdoors. The widespread use of new products and building materials, as well as improved insulation for energy efficiency, has resulted in increased concentrations of volatile organic compounds (VOCs). These VOCs originate mainly from paints and solvents, carpets and furniture, and cleaning agents, and are also emitted by humans. Elevated VOC levels can have a negative impact on well being, comfort, and cognitive abilities. Exposure to high levels of VOCs can be avoided or significantly reduced by regular ventilation, air purification and removal of strong VOC sources. The Total VOC (TVOC) concept has been established as a practical time and cost-effective method of surveying indoor environments for contamination. Sensirion’s multi-pixel gas sensor SGP enables measurement of TVOC levels and thus helps to increase the efficiency of ventilation and air purification, and increases awareness of VOC sources and indoor air pollution.

What Are VOCs?

The widespread use of new products and building materials activities, and indoor chemical reactions. Exceptionally high VOC has resulted in increased concentrations of indoor pollutants, in levels are typically found in new buildings or after renovation. Fur- particular volatile organic compounds (VOCs). Nowadays, most ther, when using products that contain VOCs, such as air fresh- people spend more than 20 hours per day indoors where VOC eners or cleaning agents, people expose themselves and others concentrations are more than five times higher than outdoor con- to high pollutant levels that can persist long after the activity has centrations1. VOCs originate from a number of different possible finished. VOCs include a wide range of chemical compounds, the sources, like building materials, tobacco smoke, people and their most common of which are listed in Table 1 below.

Typical VOC Sources Compound Class Example Compounds

Cleaning agents Aliphatic hydrocarbons, organochlorides Tetrachloroethylene

Solvents Aliphatic and aromatic hydrocarbons Heptane, decane, toluene, xylene

Cosmetics Terpenes, ketones Eucalyptol, limonene

Consumer products Terpenes, aromatic hydrocarbons Limonene, α-Pinene, toluene

Carpets and flooring Esters, aliphatic and aromatic hydrocarbons Butylacetate, heptane

Paints Alcohols, aldehydes Isobutanol

Human occupants Acetone, methanol, ethanol

Table 1 Typical indoor VOCs and their sources 2

1 EPA – the total exposure assessment methology (TEAM) study (1987), Saarela et al., Atmosph. Environ. 37, 5563 (2003) 2 See e.g. Kataoka et al. – Chap. 9 in Mass Spectrometry, Advanced Gas Chromatography - Progress in Agricultural, Biomedical and Industrial Applications (2012) Potential Health Effects of High VOC Concentrations

SENSORY IRRITATION COGNITIVE ABILITIES SICK BUILDING SYNDROME A number of systematic human expo- Poor indoor air quality can lead to The sick building syndrome5 includes a sure studies have shown various adverse decreased cognitive function resulting variety of health and comfort effects health effects caused by exposure to in significant impacts on productivity, associated with the time spent in build- elevated VOC levels3. Among the effects learning, and safety. Recent studies have ings with, among other factors, elevated reported by participants are dryness and demonstrated clear negative effects of VOC levels. Symptoms of the sick building irritation of the eye, the nose and the elevated VOC levels on cognitive abilities syndrome include headaches, mucous throat, headaches, and dizziness. such as strategic thinking and decision membrane irritation, asthma-like symp- making4. toms, skin irritation and dryness.

Steps to Reduce VOC Levels

VENTILATION Regular ventilation is an effective way to reduce exposure to VOCs. This can be done either by an automatic demand-controlled ventilation sys- SOURCE CONTROL tem equipped with suitable sensors, Most national governmental bodies or by natural ventilation through open provide guidelines and recommenda- windows and doors. tions on avoiding and removing VOC sources in indoor environments6.

AIR PURIFICATION Air cleaning devices equipped with suitable filters are an effective way to reduce the concentration of VOCs in indoor air, in particular in locations where ventilation with outside air is not appropriate.

3 Molhave, Indoor Air 4, 357 (1991), Kjaergaard et al. Atmosph. Environ. 25a, 14 17- 1426 (1991), Otto et al, Neurotoxicol. Teratol., 12, 649 (1990) 4 Allen et al., Environ. Health Perspect. 124, 805 (2016) 5 Godish, T.: Sick Buildings – Definition, Diagnosis and Mitigation, Boca Raton: Lewis Publishers (1995) 6 See e.g., https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality The Benefits of Measuring VOCs

An effective reduction of VOC exposure requires the monitoring of VOC levels using suitable sensors. A large number of applications such as ventilation controls, air purifiers, or Internet-of-Things devices benefit from the integration of VOC sensors.

CREATE AWARENESS MAKE DEVICES SMARTER MAKE DEVICES ENERGY EFFICIENT Indication of the total VOC levels helps Enable the operation of autonomous Save energy by operating ventilation and air people to better understand their living devices; for example, automatic operation purification devices only when needed; for environment and to identify possible of an air purifier. example, demand-controlled ventilation. sources of indoor air pollutants; for example, monitoring of air quality with a baby cam.

Guidelines for VOCs and the TVOC Concept

The term total VOC (TVOC) refers to the total concentration of Japan). Recommended TVOC levels of IAQ that are considered VOCs present simultaneously in the air. The TVOC concept is acceptable range from 0.6 to 1 mg/m3. The German Health De- used as a practical time and cost-effective method of surveying partment defines TVOC levels as shown inTable 2. The TVOC indoor environments for contamination. Global consensus has levels and the corresponding recommendations are based on resulted in the emergence of guidelines for TVOC standards of the results of a large number of controlled exposure studies that indoor air quality (IAQ) issued by governmental organizations in established a relationship between increased TVOC levels and different countries (e.g. Australia, Finland, Germany, Hong Kong, adverse health effects.

Level Hygienic Rating Recommendation Exposure Limit TVOC [ppb]

5 Use only if unavoidable / Situation not acceptable hours 2200 – 5500 Unhealty Intense ventilation necessary

4 Intensified ventilation / airing necessary Major objections < 1 month 660 – 2200 Poor Search for sources

3 Intensified ventilation / airing recommended Some objections < 12 months 220 – 660 Moderate Search for sources

2 No relevant objections Ventilation / airing recommended no limit 65 – 220 Good

1 No objections Target value no limit 0 – 65 Excellent

Table 2 TVOC guidelines issued by the German Federal Environmental Agency 7

7 Bundesgesundheitsbl - Gesundheitsforsch - Gesundheitsschutz 2007, 50:990–1005: Beurteilung von Innenraumluftkontaminationen mittels Referenz- und Richtwerten Sensirion’s Environmental Sensor Solutions

With the SGP, Sensirion provides a metal-oxide-based VOC sensor for indoor air quality applications. The sensing element features an unmatched robustness against contaminating gases present in real-world applications. This enables a unique long-term stability and low drift. The SGP features a TVOC and CO2 equivalent signal via an I2C interface, a small DFN package (2.45 x 2.45 x 0.9 mm3), and a dust and water protection membrane. These characteristics make the SGP easy to integrate into a large variety of applications such as air purifiers or smart home devices.

Sensirion’s sensor solutions provide detailed and reliable data on further key environmental parameters such as humidity, temperature, particulate matter (PM2.5), and CO2. Sensirion’s portfolio of environmental sensors opens up numerous possibilities to create smarter devices that improve our comfort and well being, and increase energy efficiency in various applications.

CO2

Environmental VOCSensing PM2.5

RH / T Sensing. Anytime. Anywhere. 1-900061-01 / 170510-VOC-E

SWITZERLAND Sensirion AG Laubisruetistrasse 50 8712 Staefa Switzerland Phone +41 44 306 40 00 Fax +41 44 306 40 30 [email protected] www.sensirion.com

UNITED STATES Sensirion Inc. 11 East Adams, Suite 220 Chicago, IL 60603 United States Phone +1 312 690 5858 [email protected] www.sensirion.com

CHINA Sensirion China Co. Ltd. Room 1006, Tower 1 Excellence Meilin Center Plaza (Excellence City) ZhongKang Road Shangmeilin Futian District, Shenzhen 518049 P.R. China Phone +86 755 8252 1501 Fax +86 755 8252 1580 [email protected] www.sensirion.com.cn

JAPAN Sensirion Japan Co. Ltd. Takanawa Kaneo Bldg. 4F 3-25-22, Takanawa Minato-ku, Tokyo 108-0074 Japan Phone +81 3 3444 4940 Fax +81 3 3444 4939 [email protected] www.sensirion.co.jp

KOREA Sensirion Korea Co. Ltd. 14056, #1809-#1813 Gumkang Penterium A, 282, Hagui-Ro, Dongan-Gu Anyang-Si, Gyeonggi-Do South Korea Phone +82 31 337 7700~3 Fax +82 31 337 7704 [email protected] www.sensirion.co.kr

TAIWAN Sensirion Taiwan Co. Ltd. Rm. 2, 15F, No. 223, Fuxing 2nd Rd Zhubei City Hsinchu County, 30271 Taiwan, R.O.C. Phone +886 3 5506701 Fax +886 3 5506703 [email protected] www.sensirion.com